Teenage Activities and Postures when Passengers in a Vehicle Environment

An observational investigation was first conducted to identify the common activities of teenage occupants in a vehicle environment. These included playing or texting on a cell phone, grabbing objects in a schoolbag positioned in the footwell, applying make-up while looking in the visor mirror (female), texting with legs crossed (male), looking down at an object, reaching for objects, and changing the radio. These activities were simulated in a static user study. The back of the head-to-head restraint anterior surface was 2.1 \ub1 2.7 cm for male volunteers and 3.5 \ub1 2.2 cm for female volunteers while normally seated. In comparison to when normally seated, the head moved 8.0 \ub1 3.8 cm and 4.3 \ub1 2.8 cm respectively when the volunteers were interacting with a cell phone. The back of the head-to-head restraint anterior surface was 59.4 \ub1 5.9 cm for the male volunteers and 55.8 \ub1 5.1 cm for the female volunteers when grabbing a book in the footwell area. The results were, however, similar (65.7% \ub1.8.0% v 65.9% \ub1.6.4%) when normalized by seated height. The head rotated 27.2 \ub1 14.7 deg in males and 19.1 \ub1 8.9 deg by females when playing a game on the cell phone. The results of this study highlight the increase in head-to-head restraint and head rotation during common activities conducted by teenagers when riding in the front-seat

Foot-Ankle Joints Responses. Epidemiology, Biomechanics and Mathematical Modeling

The purpose of this thesis is to acquire better knowledge of foot-ankle injuries because of their increasing importance in car crashes. Three approaches were used: epidemiology, biomechanics and mathematical modeling. The knowledge is intended to serve as a basis development of dummies and protective systems in order to reduce the frequency and cost of foot-ankle injury. In the epidemiological approach, the influence on foot-ankle injuries of impact location, seating position and age were investigated using Swedish insurance data. Impact location and seating position were of greater significance than age. The results also indicated that both intrusion and local deceleration in the footwell area need to be considered as causal factors for foot-ankle injuries in frontal impacts. However, the role of foot-controls on lower leg biomechanics and kinematics remains unclear. In the biomechanical approach, a new method was developed to determine the center of rotation (CR) and moment-angle characteristics of the ankle and subtalar joints quasi-statically under four basic movements: dorsiflexion, plantarflexion, inversion and eversion. Human subtalar and ankle-subtalar joints were tested in their natural range of motion (ROM) and to the first sign of joint failure. The results showed that the CR of ankle-subtalar joints was not fixed but moved with calcaneal rotation. CR was near the ankle joint in the dorsiflexion/plantarflexion ROM. In inversion/eversion ROM, the CR of the ankle-subtalar joints coincided with the CR of the subtalar joint. The moment-angle characteristics were determined at a fixed CR. From these results, the stiffness of the ankle-subtalar and the subtalar joints were calculated, and their contribution was estimated. Average moment and angle failure levels were determined. As another part of the biomechanical approach, the stress-strain characteristics of 7 foot-ankle ligaments were determined quasi-statically. Using the results from isolated ligament tests and ankle-subtalar joint biomechanics, a physical model of the human foot-ankle was developed to investigate ligament injury mechanisms in 2-D loading. The physical model was used as a first step for the development of a mathematical model. In the mathematical approach, MADYMO models of the Hybrid III, advanced Hybrid III (GM/FTSS), and a human lower leg were developed. The models were validated in quasi-static loading. A parameter investigation was carried out to evaluate the effect of crash acceleration, toepan intrusion and toepan rotation. Acceleration and intrusion influenced dorsiflexion responses, while toepan rotation affected inversion responses. The mathematical models were found useful to investigate crash configurations, safety-countermeasures and injury parameters since the models provide additional information not otherwise obtainable with the current Hybrid III lower leg

Size and age of fatal drivers by crash type, vehicle type and gender

Objective: The objective of this study was to determine the physical characteristics of fatal drivers in motor vehicle crashes with focus on rear impacts. Methods: 1998 to 2020 FARS data was analyzed for height, weight, and age of fatal drivers. The data was queried by gender, crash type and vehicle type. Results: The average fatal driver weighed 80.4 kg, was 173.4 cm tall, and was 43 years old. Females were 16.0 kg lighter and 14.2 cm shorter than males on average. The height was 151.2 cm for the 5th percentile female, 177.0 cm for the 50th male and 188.9 cm for the 95th male. The weight of fatal drivers increased linearly with calendar year. The increase rate was greater in females than in males. About 3% of fatal drivers were involved in rear crashes, 39.9% in frontal crashes and 36.8% in rollovers. The average fatal driver was 172.5 cm tall and weighed 81.0 kg in rear impacts. They were similar in height and weight to the overall sample. The average fatal driver in rear impacts was 46 years old, 3 years older than the overall average. Pickup truck drivers weighed 85.4 kg and were 176.8 cm tall on average. They were heavier and taller than passenger car drivers on average, which were 78.0 kg and 172.2 cm. Fatally injured minivan drivers were 10 years older than fatally injured passenger car drivers on average. The findings are compared with ATDs (anthropometric test devices) used in sled and crash testing. Conclusion: The average weight of fatal drivers increased with calendar year. The average size of fatal drivers was similar by crash types. Fatal drivers were older in rear impacts.</p

Severe injury in multiple impacts: Analysis of 1997–2015 NASS-CDS

<p><b>Purpose</b>: This is a descriptive study of the incidence and risk for severe injury in single-impact and multi-impact crashes by belt use and crash type using NASS-CDS.</p> <p><b>Methods</b>: 1997–2015 NASS-CDS data were used to determine the distribution of crashes by the number of impacts and severe injury (Maximum Abbreviated Injury Score [MAIS] 4+F) to >15-year-old nonejected drivers by seat belt use in 1997+ MY vehicles. It compares the risk for severe injury in a single impact and in crashes involving 2, 3, or 4+ impacts in the collision with a focus on a frontal crash followed by other impacts.</p> <p><b>Results</b>: Most vehicle crashes involve a single impact (75.4% of 44,889,518 vehicles), followed by 2-impact crashes (19.6%), 3-impact crashes (5.0%) and 4+ impacts (2.6%). For lap–shoulder-belted drivers, the distribution of severe injury was 42.1% in a single impact, 29.3% in 2 impacts, 13.4% in 3 impacts, and 15.1% in 4+ impact crashes. The risk for a belted driver was 0.256 ± 0.031% in a single impact, 0.564 ± 0.079% in 2 impacts, 0.880 ± 0.125% in 3 impacts, and 2.121 ± 0.646% in 4+ impact. The increase in risk from a single crash to multi-impact collisions was statistically significant (<i>P</i> < .001).</p> <p>In a single impact, 53.8% of belted drivers were in a frontal crashes, 22.4% in side crashes, 20% in rear crashes, and 1.7% in rollover crashes. The risk for severe injury was highest in a rollover at 0.677 ± 0.250%, followed by near-side impact at 0.467 ± 0.084% and far-side impact at 0.237 ± 0.071%. Seat belt use was 82.4% effective in preventing severe injury (MAIS 4+F) in a rollover, 47.9% in a near-side impact, and 74.8% in a far-side impact.</p> <p>In 2-impact crashes with a belted driver, the most common sequence was a rear impact followed by a frontal crash at 1,843,506 (21.5%) with a risk for severe injury of 0.100 ± 0.058%. The second most common was a frontal impact followed by another frontal crash at 1,257,264 (14.7%) with a risk of 0.401 ± 0.057%. The risk was 0.658 ± 0.271% in a frontal impact followed by a rear impact. A near-side impact followed by a rear crash had the highest risk for severe injury at 2.073 ± 1.322%.</p> <p><b>Conclusions</b>: Restraint systems are generally developed for a single crash or sled test. The risk for severe injury was significantly higher in 2-, 3-, and 4+-impact crashes than a single impact. The majority (57.9%) of severe injuries occurred in multi-impact crashes with belted drivers. The evaluation of restraint performance warrants additional study in multi-impact crashes.</p

Belted driver fatalities: Time of death and risk by injury severity

<p><b>Purpose</b>: This is a descriptive study of the fatality risk by injury severity and time of death for lap–shoulder-belted drivers without ejection in modern vehicles. It also determined the body region for severe injuries experienced by belted drivers using the most recent federal crash data.</p> <p><b>Methods</b>: 1997–2015 NASS-CDS data were evaluated for fatally injured lap–shoulder-belted drivers without ejection in light vehicles of 1997+ model year (MY). The severity of injuries sustained by belted drivers was assessed by the Maximum Abbreviated Injury Scale (MAIS) and individual injuries by Abbreviated Injury Scale (AIS) and body region. The change in fatality risk with MAIS was fit with a Logist function. Time of death was determined using the variable DEATH, which is reported hourly in unequal intervals up to 24 h and then daily up to 30 days after the crash. The fraction (<i>f</i>) and cumulative fraction (<i>F</i>) of the deaths are reported for each time period up to 30 days. A power or logarithmic curve was fit to the data using the trendline functions in Excel.</p> <p><b>Results</b>: The NASS-CDS sample included 20,610,000 belted drivers with 37,974 fatalities from 1997 to 2015. The fraction of driver deaths increased with maximum injury severity (MAIS). For example, 17.4% of drivers died within 30 days with MAIS 4 injury. Virtually all drivers (99.7%) died with MAIS 6 injury. The change in fatality risk with injury severity was <i>r</i> = [1 + exp^{(10.159 − 2.088MAIS)}]⁻¹, <i>R</i>² = 0.950. Overall, there were 19,772 driver deaths with MAIS 4–6 injury and 13,059 with MAIS 0–3 injury. In addition, 44.7% of driver deaths occurred within 1.5 h of the crash, 56.7% within 2.5 h, and 64.6% within 4.5 h after the crash. The cumulative fraction of the deaths (<i>F</i>) up to 30 days was fit with a logarithmic function. It was <i>F</i> = 0.0739ln(<i>t</i>) + 0.5302, <i>R</i>² = 0.976, for deaths after 3.5 h. There were 19,772 driver deaths with 52,130 AIS 4+ injuries. On average, the driver experienced 2.64 AIS 4+ injuries most commonly to the head (44.5%) and thorax (38.1%).</p> <p><b>Conclusions</b>: The risk for belted driver deaths exponentially increased with MAIS. A majority of deaths occurred within 2.5 h of the crash. On average, fatally injured drivers experienced 2.64 AIS 4+ injuries, primarily to the head and thorax.</p

Concussion, Diffuse Axonal Injury, and AIS4+ Head Injury in Motor Vehicle Crashes

<div><p><b>Purpose</b>: This is a descriptive study of the annual incidence of brain injuries in motor vehicle crashes by type, seat belt use, and crash severity (delta <i>V</i>) using national accident data. The risk for concussion, diffuse axonal injury (DAI), and severe head injury was determined.</p><p><b>Methods</b>: 1994–2011 NASS-CDS was analyzed to estimate the number of brain injuries annually in nonejected adults involved in motor vehicle crashes. Crashes were grouped by front, side, rear, and rollover, and the effect of belt use was investigated. Light vehicles were included with model year 1994+. Head injuries were identified as concussion, DAI, severe head injury (Abbreviated Injury Scale [AIS] 4+), and skull fracture. The annual incidence, risk, and rate for different types of head injury were estimated with standard errors.</p><p><b>Results</b>: Motor vehicle crashes involved 33,191 ± 7,815 occupants with concussion, 5,665 ± 996 with AIS 4+ head injuries, 986 ± 446 with DAI, and 3,300 ± 531 with skull fracture annually. The risk was 1.64 ± 0.39% for concussion, 0.28 ± 0.05% for severe head injury (AIS 4+), 0.05 ± 0.02% for DAI, and 0.16 ± 0.03% for skull fracture in tow-away crashes. The risk for severe head injury (AIS 4+) was highest in rollovers (0.74 ± 0.16%) and lowest in rear impacts (0.17 ± 0.05%). Head injury risk depended on seat belt use, crash type, and crash severity (delta <i>V</i>). Seat belt use lowered the risk for AIS 4+ head injury by 74.8% and skull fracture by 73.2%.</p><p><b>Conclusions</b>: Concussions occur in about one out of 61 occupants in tow-away crashes. The risk was highest in rollover crashes (4.73 ± 1.09%) and it was reduced 69.2% by seat belt use. Severe brain injuries occurred less often and the risk was also reduced by seat belt use.</p></div

Driver injury in near- and far-side impacts: Update on the effect of front passenger belt use

<p><b>Purpose</b>: This is a study that updates earlier research on the influence of a front passenger on the risk for severe driver injury in near-side and far-side impacts. It includes the effects of belt use by the driver and passenger, identifies body regions involved in driver injury, and identifies the sources for severe driver head injury.</p> <p><b>Methods</b>: 1997–2015 NASS-CDS data were used to investigate the risk for Maximum Abbreviated Injury Scale (MAIS) 4 + F driver injury in near-side and far-side impacts by front passenger belt use and as a sole occupant in the driver seat. Side impacts were identified with GAD1 = L or R without rollover (rollover ≤ 0). Front-outboard occupants were included without ejection (ejection = 0). Injury severity was defined by MAIS and fatality (F) by TREATMNT = 1 or INJSEV = 4. Weighted data were determined. The risk for MAIS 4 + F was determined using the number of occupants with known injury status MAIS 0 + F. Standard errors were determined.</p> <p><b>Results</b>: Overall, belted drivers had greater risks for severe injury in near-side than far-side impacts. As a sole driver, the risk was 0.969 ± 0.212% for near-side and 0.313 ± 0.069% for far-side impacts (<i>P</i> < .005). The driver's risk was 0.933 ± 0.430% with an unbelted passenger and 0.596 ± 0.144% with a belted passenger in near-side impacts. The risk was 2.17 times greater with an unbelted passenger (NS). The driver's risk was 0.782 ± 0.431% with an unbelted passenger and 0.361% ± 0.114% with a belted passenger in far-side impacts. The risk was 1.57 times greater with an unbelted passenger (<i>P</i> < .10). Seat belt use was 66 to 95% effective in preventing MAIS 4 + F injury in the driver. For belted drivers, the head and thorax were the leading body regions for Abbreviated Injury Scale (AIS) 4+ injury. For near-side impacts, the leading sources for AIS 4+ head injury were the left B-pillar, roof, and other vehicle. For far-side impacts, the leading sources were the other occupant, right interior, and roof (8.5%).</p> <p><b>Conclusions</b>: Seat belt use by a passenger lowered the risk of severe driver injury in side impacts. The reduction was 54% in near-side impacts and 36% in far-side impacts. Belted drivers experienced mostly head and thoracic AIS 4+ injuries. Head injuries in the belted drivers were from contact with the side interior and the other occupant, even with a belted passenger.</p

Driver and front passenger injury in frontal crashes: Update on the effect of unbelted rear occupants

<p><b>Purpose</b>: This is a study of the influence of an unbelted rear occupant on the risk of severe injury to the front seat occupant ahead of them in frontal crashes. It provides an update to earlier studies.</p> <p><b>Methods</b>: 1997–2015 NASS-CDS data were used to investigate the risk for severe injury (Maximum Abbreviated Injury Score [MAIS] 4+F) to belted drivers and front passengers in frontal crashes by the presence of a belted or unbelted passenger seated directly behind them or without a rear passenger. Frontal crashes were identified with GAD1 = F without rollover (rollover ≤ 0). Front and rear outboard occupants were included without ejection (ejection = 0). Injury severity was defined by MAIS and fatality (F) by TREATMNT = 1 or INJSEV = 4. Weighted data were determined. The risk for MAIS 4+F was determined using the number of occupants with known injury status MAIS 0+F. Standard errors were determined.</p> <p><b>Results</b>: The risk for severe injury was 0.803 ± 0.263% for the driver with an unbelted left rear occupant and 0.100 ± 0.039% with a belted left rear occupant. The driver's risk was thus 8.01 times greater with an unbelted rear occupant than with a belted occupant (<i>P</i> <.001). With an unbelted right rear occupant behind the front passenger, the risk for severe injury was 0.277 ± 0.091% for the front passenger. The corresponding risk was 0.165 ± 0.075% when the right rear occupant was belted. The front passenger's risk was 1.68 times greater with an unbelted rear occupant behind them than a belted occupant (<i>P</i> <.001). The driver's risk for MAIS 4+F was highest when their seat was deformed forward. The risk was 9.94 times greater with an unbelted rear occupant than with a belted rear occupant when the driver's seat deformed forward. It was 13.4 ± 12.2% with an unbelted occupant behind them and 1.35 ± 0.95% with a belted occupant behind them.</p> <p><b>Conclusions</b>: Consistent with prior literature, seat belt use by a rear occupant significantly lowered the risk for severe injury to belted occupants seated in front of them. The reduction was greater for drivers than for front passengers. It was 87.5% for the driver and 40.6% for the front passenger. These results emphasize the need for belt reminders in all seating positions.</p